This invention relates to configuring power converters.
Typically, a series of predetermined power converter configurations are supplied by power converter manufacturers. Several manufacturers, for example, Vicor Corporation.TM., provide an automatic selection system which compares user specified power converter functional requirements (e.g., input and output voltage and output power) and physical requirements (e.g., number of pins and package size) to the functionality offered by a variety of preconfigured models (e.g., a power converter `configuration` is a predefined combination of component parts which results in a converter which meets a predefined set of functional and physical requirements) of converters and selects a preconfigured model, or combination of preconfigured models, that meet the user's needs. If the user's needs cannot be met, the user is informed and requested to change his requirements.
If a customer needs a power converter with particular requirements that cannot be met by a preconfigured model within the manufacturer's product line, then a power converter designer, using basic equations and experience, may be asked to design a power converter configuration that meets the customer's needs. In general, a particular set of functional and physical requirements may be met with many different power converter configurations. As a result, two designers with the same customer information may come up with different power converter configurations. Designers generally use rules of thumb and experience to try to achieve good overall performance (e.g., high conversion efficiency). However, due to time and resource constraints, a designer can only try a limited number of different configurations.
General Electric Corporation.TM. has offered prepackaged modular building blocks for configuring switching power supplies. Each building block (e.g., rectifier block, switch block, output filter block) forms a portion of a switching power supply and each is available in various voltage and current ratings to allow configuring supplies of varying input voltage, output voltage, and power ratings. A microcomputer-based software package aids the user in selecting those building blocks which, when connected together, will result in a power supply which meets the user's functional requirements. The software selects those pre-defined blocks which will result in a certain combination of input voltage, output voltage, and power level.
There is a large body of literature regarding mathematical methods for optimizing active or passive circuit performance. In general, these methods rely on having objective sets of functions which describe the circuit, or suitably accurate models, and then using mathematical minimization and maximization methods (e.g., least-squares, gradient-projection, steepest descent) to find a single, theoretically optimal, solution which achieves some circuit performance objective, or objectives, subject to constraints. In some cases, the optimization method is linked with a circuit simulator, such as SPICE. See, for example, Lu and Adachi, "A Parameter Optimization Method for Electronic Circuit Design Using Stochastic Model Function," Electronics and Communications in Japan, Part 3, Vol. 75, No. 4, 1992, pp. 13-25; Nye, et al, "DELIGHT.SPICE: An Optimization-Based System for the Design of Integrated Circuits," IEEE Transactions on Computer-Aided Design, Vol. 7, No. Apr. 4, 1988, pp. 501-519; Ivanov, et al, "Computer-Aided Optimization of the Parameters of Electronic Circuits," Telecommunications and Radio Engineering, Part 2 (Radio Engineering), Vol. 26, No. 11, November 1971, pp. 124-128.
Linear Technology Corporation, Milpitas, Calif., USA, offers a software based power supply design program called SwitcherCAD; National Semiconductor Corporation, Santa Clara, Calif., USA, offers a software based power supply design program called Simple Switcher. Both programs accept a set of predefined functional specifications and generate parts lists and schematics for a power supply which meets the specifications. Both can produce designs for different topologies (e.g., isolated flyback, non-isolated PWM buck). The user of the programs can modify component values and other design parameters and observe the effects on performance, e.g., conversion efficiency. Both programs use pre-defined equations for generating a solution.